In the past, yellow displays have been frequently been employed for the displays of postage meters. The color yellow has been found to be necessary for such displays in order to enable the displays to be visible by an operator in a dark environment as well as in the presence of bright sunlight or other light.
While displays of this type may employ LEDs arranged to visibly display a plurality of characters, a display of this type requires a relatively large amount of power. In addition, when the LEDs are of a specific color, such as yellow, it is necessary to color match all of the LEDs, since the human eye response peaks in the yellow range. Accordingly a display of this type is expensive to produce. In addition, when LEDs are employed in a display panel, in combination a logic circuit, it may be necessary to provide a 5 volt supply for the logic circuits as well as a 3 volt supply for the LEDs.
U.S. Pat. No. 4,959,642 discloses an LCD panel wherein backlighting is provided, primarily only for low light conditions, by LEDs. In the arrangement of this patent, however, the LEDs are provided in a relatively complex circuit to be energized by the power of a source that is being measure by the LCD circuitry, to permit the conventional LCD device to be visible in low ambient light conditions.